Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

[Nivekt]

I discovered the other day that the starboard manifold is cracked. No water is leaking from the crack, but its only a matter of time before she goes.

Ive contacted Ebasic power(http://bpi.ebasicpower.com/index.php) and this is the replacement they told me was the correct one: http://bpi.ebasicpower.com/mm5/merchant.mvc?Screen=PROD&Store_Code=eBasicPower&Product_Code=OSC2441

So, based upon my issue the parts from Ebasic power I am prepared to order are the following:

OSC2441 Exhaust Manifold GM V8 OMC Log (Starboard) $169.00
GLM22280 Manifold Rubber Cap 1-1⁄4", OMC (Qty:3) $7.95(each)
OSC9863-MK Riser Mounting Kit, OMC (OSC9863) $7.95
OSC244MK Manifold Mounting Kit (2441, 2442, 52374) Volvo, OMC $15.95

Total comes out to about $220.00 with shipping. Pretty damn cheap considering what Im working with here. Can anyone give me some input here? Am I missing anything? The high rise hose to the elbow looks to be in really good shape so I dont think I need to change it out also.
Thanks for your time.

 

[cr2k]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

On 79 boat I would replace both manifolds and risers. How far behind do you think the others are? Manifolds and risers are maintenance items much like the impeller. Over 15 years in fresh water is borrowed time, 10 or less in salt.
BTW check on eBay to. I have found new ones very cheap on there.

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Cracked and leaking on the outside is not all that big a deal.....

But leaking on the inside sometimes results in destroying the engine. And you usually can't see inside leaks.....

I would also inspect the risers too. If they are questionable, I would replace them too. (both of them)

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Thanks for the input guys. The port side manifold and both risers look okay. I would of course prefer to replace them all anyway. Ill start with the starboard side and get to the port when my wallet permits. From your experience, do the parts that ebasicpower has listed seem to be the correct ones?

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

The port side manifold and both risers look okay.

They way they "look' on the outside means nothing.

At the minimum, take BOTH sides apart and inspect, in any case, you need to replace the riser gaskets on both sides. Look for rust trails on the inside and good clean sealing surfaces. If they don't seal, you'll be replacing the engine in the not to distant future.

I have bought some parts from eBasicpower but not manifolds.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

They way they "look' on the outside means nothing.

At the minimum, take BOTH sides apart and inspect, in any case, you need to replace the riser gaskets on both sides. Look for rust trails on the inside and good clean sealing surfaces. If they don't seal, you'll be replacing the engine in the not to distant future.

I have bought some parts from eBasicpower but not manifolds.

Gotcha. Will do.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Pulled both manifolds and risers today. Everything is pretty well rusted out. Found a huge crack in the starboard riser and a small hairline crack in the port manifold. I went ahead and ordered this kit as well. Not too bad a price for everything: http://www.ebay.com/itm/19068727242...ename=ADME:L:OC:US:3160&vxp=mtr#ht_719wt_1169

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Good plan!

You probably prevented an engine replacement!

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Good plan!

You probably prevented an engine replacement!

Yeah, I figured better safe then sorry. There wasn't any sign of rust in the actual exhaust chambers but the last thing I want is to be constantly worried when I'm out on the lake this summer. $560 is a lot easier to swallow than $1500+ for a new engine.

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Yeah, I figured better safe then sorry. There wasn't any sign of rust in the actual exhaust chambers but the last thing I want is to be constantly worried when I'm out on the lake this summer. $560 is a lot easier to swallow than $1500+ for a new engine.

Just be absolutely sure you drain the manifolds and block before freezing temps occur............remove all block and manifold plugs, use a piece of wire or thin screwdriver etc to poke in there to get the rust flakes and other debris out to ensure good draining.

We've all been there!


Cheers,


Rick

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Just be absolutely sure you drain the manifolds and block before freezing temps occur............remove all block and manifold plugs, use a piece of wire or thin screwdriver etc to poke in there to get the rust flakes and other debris out to ensure good draining.

We've all been there!

Cheers,


Rick

Thanks for the tips. Before I pulled these manifolds I had no idea about draining them after each use of the boat. I left water in them all winter long. When I removed the drain plugs all kinds of nasty, rusty water came out. I have no idea how long they have been cracked but I honestly didnt know to look for it. The winter here was very mild and I dont think it ever got to freezing temps.

Do you think I should replace the exhaust hoses while Ive got everything torn apart? The rubber is still nice and pliable but there are grooves worn in from where the worm gear clamps have held them in place. Sorry for the poor quality of the picture, best my cell phone could do.

Also, where on the block is the plug(s) to drain it?

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

I got the new manifolds and risers in yesterday. Bolted them together and all looks well enough. I used my compressor to blow them out and a surprising amount of rust flakes came out of one of the risers. All the water channels look fine though.

Should I sand off the paint and smooth the surface of where the manifold meets the gasket? It seems smooth with it being painted but I didnt know how important it was to have a perfectly smooth surface once I bolt it up to the block. Of course the gasket is a crush gasket so it should fill any voids.

I still have to clean out the rubber exhaust hoses. before mating those to the risers to then install. The rubber is still very pliable but has some build up on the inside that I would like to scrub out.

 

[bruceb58]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Check your thermostat housing too. The outlets of it to the manifolds can really get clogged as well.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Check your thermostat housing too. The outlets of it to the manifolds can really get clogged as well.

Thanks. I plan to. I was going to soak it in CLR and then scrub it with a small wire brush to remove any build up.

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

I am surprised at how lucky you are that you DON'T have a cracked block. Maybe you don't get freezing temps there much.....

No matter, call yourself "lucky" and ensure that you drain everything in the future.

I would re-use those hoses too if they're not cracked thru....

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

I am surprised at how lucky you are that you DON'T have a cracked block. Maybe you don't get freezing temps there much.....

No matter, call yourself "lucky" and ensure that you drain everything in the future.

I would re-use those hoses too if they're not cracked thru....

Well ****. Finally had a chance to get out and look over the block and found a 5" crack on the port side. I guess Ill JB weld it and hope for the best. I also noticed that the two fore studs on both sides that hold the exhaust manifold on are not installed. Its been like this since I bought the boat 3 years ago. Can anyone guess as to why they would not be there? Contrary to what the picture shows, the threads seems good. The port side has a lot of gunk in it that needs to be cleaned out though(pic)

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Engines that are cracked on the outside are frequently cracked on the inside.

You will find out soon enough. The oil will become contaminated with water quickly.

If it is, you might want to peruse the wrecking yards for a truck engine. (350 GM V-8 right?)

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Yes, gm 350. I presume the only way to check for water in the oil is to pump it all out, correct?

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Yes, gm 350. I presume the only way to check for water in the oil is to pump it all out, correct?

That's a good way.

But if it cracked after it was run last, there might not be much water in there.

I am not a believer in using JB Weld or other epoxy to "fix" engine blocks.

Other people have used it successfully for more than a few years....

There's not much to lose (except more screwing around with the boat when you could be boating with a reliable engine)
if it doesn't work, you'll have to pull the engine anyway....

There's so many 350 engines sitting in wrecking yards that it's almost easier to just get one and swap it out (assuming you get a good one)

A lot of times you can buy one from someone on craigslist that's in a running pickup that you can hear run.....

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

That's a good way.

But if it cracked after it was run last, there might not be much water in there.

I am not a believer in using JB Weld or other epoxy to "fix" engine blocks.

Other people have used it successfully for more than a few years....

There's not much to lose (except more screwing around with the boat when you could be boating with a reliable engine)
if it doesn't work, you'll have to pull the engine anyway....

There's so many 350 engines sitting in wrecking yards that it's almost easier to just get one and swap it out (assuming you get a good one)

A lot of times you can buy one from someone on craigslist that's in a running pickup that you can hear run.....

I last ran the boat hooked up to the hose two weeks ago. I ran it for about 10-15 minutes or so. Long enough to heat up and stabilize at 180F. It ran great, no odd color in the exhaust or anything. I assume the crack was present at that time. Hopefully that was long enough for water to weep into the oil if there is a crack present to get it there.

I certainly will start looking around for a new block now, but if the JB weld can get me by while I save to do the replacement that will be a bonus. Do you know if Im looking for a GM block that was manufactured during a certain time period? I cant imagine I can just go pick up any old GM 350 and have it be the correct one.

Another odd thing about the exhaust manifolds. At shop.evinrude.com, it shows that there are only 10 studs required to hold the exhaust manifolds in place. The old, cracked manifolds I pulled off only had holes for 5 on each side. The new manifolds have holes for 6 studs on each side and the block itself is setup to accept 6 studs. Could it be that using 5 is good enough and I dont need to install the additional stud on each side or should I err on the side of caution and go ahead and put in the extra studs? The manifolds are certainly the correct ones, they line up properly and everything.